Cisco DCIT 300-615 key terms

The Layer 2 trunk that joins two vPC switches, carries control traffic, and forwards traffic when a member port fails. It must run on a dedicated high-bandwidth link, typically a port channel.

A logical grouping identified by the same domain ID on both peer switches that defines the vPC relationship, its peer-keepalive path, and the shared virtual MAC used by member ports.

A heartbeat exchanged over the management or a routed link outside the peer-link, used to detect a peer switch failure and decide whether to suspend vPC member ports.

A port on a vPC switch that is not a member of any vPC but carries VLANs that are trunked on the peer-link, so traffic for it is forwarded across the peer-link.

The comparison of Type 1 (mandatory) and Type 2 (advisory) parameters between vPC peers. A Type 1 mismatch suspends member ports; a Type 2 mismatch only raises a syslog warning.

The condition where the peer-link fails but both vPC switches stay up, so each peer keeps forwarding independently and can create duplicate MAC addresses and loops unless the secondary peer suspends its ports.

The infrastructure protocol that synchronizes configuration and state between vPC peers over the peer-link, sending MAC, ARP, and IGMP entries so both switches forward consistently.

A Cisco Layer 2 multipathing technology that replaces STP with IS-IS-based control plane forwarding, allowing all links to be active and providing loop-free equal-cost paths in a data center fabric.

A Layer 2 loop-prevention protocol that elects a root bridge and blocks redundant ports. Troubleshooting focuses on root placement, port roles, and topology change notifications.

A bundle of physical links treated as one logical interface using LACP or static mode. Mismatched member settings, such as speed or allowed VLANs, prevent the bundle from coming up.

Link Aggregation Control Protocol, defined in IEEE 802.3ad, negotiates PortChannel membership with PDUs. Troubleshooting checks the system priority, port priority, and activity mode on both ends.

A protocol such as HSRP, VRRP, or GLBP that gives hosts a shared default gateway address. Failures usually appear as split active roles or mismatched virtual IP and group settings.

Hot Standby Router Protocol elects one active and one standby router per group using priority and preemption. Troubleshooting verifies group numbers, virtual IP, authentication, and hello timers match on peers.

The primary or secondary designation of a vPC peer, deciding which switch keeps its member ports up when the peer-link fails and which handles certain control-plane responsibilities.

Cisco Fabric Extender, a remote line card managed by a parent switch over a fabric interface. Troubleshooting checks fabric port state, FEX registration, and host interface pinning.

A spanning tree feature that err-disables a port if it receives a BPDU, protecting edge ports from accidental switch connections. Recovery requires shutdown/no shutdown or errdisable auto-recovery.

A switch state that shuts a port after a violation such as BPDU Guard, link flap, or port security. The cause is shown in show interface status err-disabled and in the syslog.

Overlay Transport Virtualization encapsulates Layer 2 frames in IP to stretch a VLAN between data centers. Troubleshooting inspects the overlay interface, adjacency, and unicast and multicast route state.

A Layer 2 overlay that encapsulates Ethernet frames in UDP with a 24-bit VNI, allowing large-scale tenant segmentation over an IP underlay and used with EVPN control planes.

VXLAN Tunnel Endpoint, the device that encapsulates and decapsulates VXLAN frames. Troubleshooting verifies NVE interface state, peer reachability, and VNI-to-VLAN mapping.

Ethernet VPN, a BGP address family that distributes MAC and IP reachability for VXLAN and other overlays, replacing flood-and-learn with a control plane for faster convergence.

Virtual Routing and Forwarding creates separate routing tables on one device. Troubleshooting checks route-target import and export, RD values, and interface-to-VRF assignment for leaked or missing routes.

The controlled exchange of prefixes between VRFs, often via a shared export and import route target. Failures typically come from mismatched route-target values or missing static or connected redistribution.

Multiprotocol BGP carries address families such as VPNv4 and EVPN. Troubleshooting checks neighbor state, route-target filtering, next-hop reachability, and the BGP router ID.

The neighbor relationship formed through hello, database exchange, and full state. Stuck states usually point to MTU, area, authentication, or network type mismatches between routers.

A difference in maximum transmission unit between neighbors that can block OSPF database exchange or silently drop large packets. Verification uses show ip ospf interface and ping with a specific size.

Bidirectional Forwarding Detection provides sub-second failure detection for routing protocols. Troubleshooting checks session state, echo mode, timers, and that both ends are enabled on the interface.

A vPC feature allowing a switch to forward traffic addressed to the peer's router MAC, avoiding hairpinning through the peer-link and reducing latency for routed traffic.

The uplink on a parent switch that connects to a FEX and carries all FEX host traffic. Troubleshooting checks its state, the associated FEX number, and pinning of host ports.

A reusable template of interface settings applied to multiple ports or virtual interfaces, often via Cisco UCS or Nexus Dashboard, so a misconfigured profile causes failures across many ports at once.

Cisco's management platform that provides fabric controller and assurance functions, including telemetry-based anomaly detection and configuration compliance for Nexus and ACI environments.